Disk Cleanup: can I uncompress compressed files?

[Kate]

We have a lot of photos which are already compressed in .tif format. Having
carried out a Disk Cleanup recently and allowed compression of older files,
I am now concerned that further compression of .tifs will have degraded my
photos. Of course, if this is the case, then the damage has already been
done, and, in future, I will not allow compression by Disk Cleanup.
Meanwhile, can I get my photos back to non-archived state, please? Just
opening them doesn`t change anything, in that the file names remain in blue.

Incidentally, I think it would be nice to be able to exclude certain file
types, or certain folders, from compression when using that facility in Disk
Cleanup.

Thanks
Kate

 

[Big Al]

We have a lot of photos which are already compressed in .tif format. Having
carried out a Disk Cleanup recently and allowed compression of older files,
I am now concerned that further compression of .tifs will have degraded my
photos. Of course, if this is the case, then the damage has already been
done, and, in future, I will not allow compression by Disk Cleanup.
Meanwhile, can I get my photos back to non-archived state, please? Just
opening them doesn`t change anything, in that the file names remain in blue.

Incidentally, I think it would be nice to be able to exclude certain file
types, or certain folders, from compression when using that facility in Disk
Cleanup.

Thanks
Kate

How much hard drive do you have? How much is free? And how much did
the compression of old files save you?

 

[Ken Blake, MVP]

We have a lot of photos which are already compressed in .tif format. Having
carried out a Disk Cleanup recently and allowed compression of older files,
I am now concerned that further compression of .tifs will have degraded my
photos. Of course, if this is the case, then the damage has already been
done, and, in future, I will not allow compression by Disk Cleanup.

No, that's not the case. The kind of compression done by Disk Cleanup
is lossless, and doesn't hurt photos or any other files in any way.
When the files are uncompressed, they will be identical to what they
were before.

 

[Big Al]

No, that's not the case. The kind of compression done by Disk Cleanup
is lossless, and doesn't hurt photos or any other files in any way.
When the files are uncompressed, they will be identical to what they
were before.

If it did degrade the files, then old .exe files would be useless when
restored.

 

[Ken Blake, MVP]

If it did degrade the files, then old .exe files would be useless when
restored.

Exactly. And as far as this kind of compression is concerned, it can't
tell the difference between an exe file and a tif.

 

[Kate]

How much hard drive do you have? How much is free? And how much did the
compression of old files save you?

I have 82GB spare HD capacity. I only ran Disk Cleanup on advice after I
installed XP SP3 and thought that the system had slowed down. Now I wish
that I hadn`t taken that advice. Too late, though. I cannot remember how
much space was saved but it probably wasn`t all that significant anyway -
which, I would guess, is probably the point you are quite rightly making.

If I cannot return our photos to a non-archived state, I suppose I could
open each one and Save As with a different name, then delete the old ones,
but it`s a daunting task. Still, if the compression format in Disk Cleanup
*is* totally lossless, and repeated opening and closing of the files will
not degrade the images at all, I probably won`t bother. I have looked
online, but couldn`t find anything that completely reassured me.

Kate

 

[Kate]

Exactly. And as far as this kind of compression is concerned, it can't
tell the difference between an exe file and a tif.

I sent off my earlier post before I saw these other replies. Thanks, guys.
I feel a lot better now!

Kate

 

[Ken Blake, MVP]

I sent off my earlier post before I saw these other replies. Thanks, guys.
I feel a lot better now!

You're welcome. Glad to help.

 

[Swifty]

Exactly. And as far as this kind of compression is concerned, it can't

tell the difference between an exe file and a tif.

Out of curiosity, can it tell the difference between a file which is
smaller when compressed and one which isn't? I've never seen a message
such as "No point compressing that file, friend" and everything I've
ever tried to compress has ended up with the green "compressed"
indicator. I've known many systems where the compressed files sometimes
ended up larger…

If I knew the answer to this, and it was what I hoped, then I would
probably turn compression on my entire \backup tree, for example.

 

[Ken Blake, MVP]

Out of curiosity, can it tell the difference between a file which is
smaller when compressed and one which isn't? I've never seen a message
such as "No point compressing that file, friend" and everything I've
ever tried to compress has ended up with the green "compressed"
indicator.

Although it might be able to do this, there is no built-in capability
to do so. So the practical answer to your question is no.

I've known many systems where the compressed files sometimes
ended up larger…

The normal result of compressing an already-compressed file is to make
it slightly larger. You get no extra compression, but you get the
overhead the extra layer of compression creates.